Multifaceted investigations on the biology of Schistosoma haematobium have led to the discovery that there probably is a causal relationship between infection of this parasite and bladder cancer. Even though a number of primates has been subjected to infection and subsequent evaluation, the S. haematobium-capuchin monkey (Cebus) combination has shown the greatest promise. Significant incidence of bladder cancer has been demonstrated by open cystotomy in hosts infected 2 plus years. Selected hosts (4 with cancer) have been subjected to bladder lesion transplant (autologous: subcutaneous, intramuscular, and subperitoneal transfer). It is proposed that these hosts with demonstrated carcinogenic potential be studied for an additional 2 years to further evaluate pertinent basic biological parameters (growth potential, metastasis, transferability) of lesions histologically recognized as cancer. These hosts will be monitored physically (palpation of lesion transfer sites), clinically (X-ray, BUN determinations, preliminary urine cytology, etc.), and parasitologically (basic host-parasite relationships associated with infection), and pathologically (cystotomy, additional tissue transfer, if warranted, etc.). Standard procedures (clinical, pathology, and parasitology) will be employed to execute the proposal outlined.